docs: def user_to_device_distance(self, dx, dy):
          """Transform a distance vector from user space to device space.
          This method is similar to :meth:`Context.user_to_device`
          except that the translation components of the CTM
          will be ignored when transforming ``(dx, dy)``.
  
          :param dx: X component of a distance vector.
          :param dy: Y component of a distance vector.
          :type x: float
          :type y: float
          :returns: A ``(device_dx, device_dy)`` tuple of floats.
  
          """
          xy = ffi.new('double[2]', [dx, dy])
          cairo.cairo_user_to_device_distance(self._pointer, xy + 0, xy + 1)
          self._check_status()
          return tuple(xy)